Dual-purpose door for aircraft



De.29,1964 A. L. STARLING Em 3,163,383

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De 29 1954 A. L. sTARLlNG ETAL 3,163,383

DUAL-PURPOSE DOOR FOR AIRCRAFT Y 4 Sheets-Sheet 2.

Filed March 18. 1963 Dec. 29, 1964 Filed March 18, 1963 A A. L. STARLINGETAL DUAL-PURPOSE DOR FOR AIRCRAFT 4 Sheets-Sheet 3 N N o 0 1n e lo r `lif e 1 :s o L n lo Q 'n q' l v (D n Ll. l

l l l 5 INVENTORS ALLEN L. STARLING JOHNNIE H. MORI BERNARD MCDERMOTT Bygnf Dec- 29, 1964 A. L. sTARLlNG ETAL 3,163,383

DUAL-PURPOSE DOOR vFR AIRCRAFT 4 Sheets-Sheet 4 I Filed March 18, 1963FlG- INVENToRs ALLEN L STARLING JoHNNlE H. MORI FIG- e BERNARD yMcDERMoTT gent United Statesy Patent 3,163,383 BUAL-PURPSE DR FR A-IAFTAlien L Starting, Los Angeles, Johnnie H. Mori, heroines,

and Bernard V. McDermott, Los Angeies, Caiif., assignors to LockheedAircraft Corporation, Eurbantr, Calif.

Fiied Mar. 18, i963, Ser. No. 265,897 7 Claims. (til. 244-129) Thepresent invention relates to a dual purpose door and more particularlyto a combined access door and a pressure relief valve. Y

Although the dual-purpose door of the present invention may be usedwherever it is desired to protect pressurized compartments or ducts, itwill be described, for purposes of illustration, but not of limitation,as employed in the leading edge of the wing of an airplane.

In connection with the leading edge of an airpiane wing, means must beprovided for deicing it and lalso means must be provided for havingaccess to the interior of the leading edge for purposes of inspectingstructural members housed therein and servicing equipment housedtherein.

The deicing operation on modern aircraft is performed by bleeding heatedair at high pressure from o .e of the engines and ducting it through aplenum disposed within the leading edge of the wing to a manifold whichdirects the heated air against the exterior surface of the leading edgeto evaporate any moisture coming in contact therewith.

Although a modulating valve is usually placed in the system to maintainthe temperature and pressure of the air within safe limits, the leadingedges of Wings have been blown off bythe air pressure building upsu'iciently to rupture the plenum. This can happen when the modulatingvalve malfunctions or when a pipe supplying the system gives way.Consequently, it has been a problem in the prior art to provide efcientmeans for maintaining a safe pressure differential between thev outsideleading edge of a wing and the interior thereof. In the past, it hasbeen the practice to assure that the pressure does not go beyond thestructural strength of the leading edge of the wing by providing as manyas 48 individual, spring-biased pressure relief valves which are mountedin individual frames along the leading edge of the wing.

Another problem in connection with aircraft resides in the necessity ofinspecting and servicing equipment inside the leading edge of the wing.lt is necessary to periodically inspect the structural members insidethe wing and to service equipment housed therein. For this purpose, ithas been the practice to employ as many as 48 separate access doorswhich are mounted in individual frames along the leading edge of thewing.

it is obvious that the employment of separate pressure relief Valves andaccess doors adds to the weight of the airplane because, in such event,separate frames and hinge assemblies must also be employed. In addition,many fasteners are required to secure the separate doors in a closedposition and the fabrication of the frames adds to the cost offabricating the wing.

lt will also be appreciated that considerable engineering design time isrequired for incorporating such a plurality of doors into the airplanestructure.

It has not been possible to employ springfbiased pressure relief doorsas access doors becausethe spring will not permit them to be opened farenough to gain access.

enumerated above and having a unique hingerstructure P y. ICC

, a pressure relief valve kemploying a leaf spring whose purpose door ofthe invention;

preload may be adjusted without replacing the spring.

Yet another object of the present invention is to provide a pressurerelief valve employing a leaf spring in such a manner that the valvewill open due to a predetermined air pressure and the same pressure willcontinue to open the valve uniformly. v According to the presentinvention, a dual-purpose door is mounted in a single frame With asingle hinge in such a manner that the door will swing about the hingeand open as doors normally do. The hinge employed resembles a butt hingehaving one portion connected to Y the door and the otherportionrconnected to a suitable framing member.

A ieaf spring is then employed to bias the door to aV kclosed positionand has its inner end connected to the door and its outer end connectedto the portion of the butt hinge which is secured to the framing member.WhenV it is desired to open the door for inspection purposes, thenormall operation of the leaf spring will not Vpermit sufficient access.Therefore, the outer end of the leaf spring is released from the portionof the butt hinge which is secured to the framing member sopthat bothends of the leaf spring will remain in afplane parallel to the plane ofthe door as it is pivoted about the'rhinge. Y

A wedge having a predeterminedshape is placed beneath the outer endl ofthe leaf spring and is contoured in such a manner that the preload ofthe spring can be adjusted and so that a predetermined pressure kwillcontinue to open the door without being resisted by the load of thespring too soon. Y

The features of the present invention which are believed to be novel areset forth with particularity in the appended claims. TheV presentinvention, both as to its organization and manner of operation, togetherwith further objects and advantages thereof, may best be understood byreference to the following description, taken in connection with theaccompanying drawings, in which: 1

FiGURE l is a plan view of the internal side of a dual'- FlGURE 2 is across-sectional View taken; along line 2-2 of FIGURE l; g

FlGURE 3 is a cross-sectional View,` similar to FG.- URE 2, with thedoor of FIGURE 1 shown in a Vpressure relieved position; Y i

FIGURE 4 is a cross-sectional View, similar to FIG- URE 2, of the doorof GURE l in a fully opened position;

FIGURE 5 is a crossfsectional view of an alternate embodiment of anouter portion of the door; and

FIGURE 6 is a View of the Fronten 5 embodiment in an actuated condition.

Referring again to the drawings, the dual-purpose doorl constituting'the present invention, generally designatedL itl, includes a door memberi2 which is swingably mount- 16 in a manner to be hereinafterdescribed.`

E The frame 16 is mounted, for example, in the leading edge of anairplane wing 24 and includes an upper header 26 and a lower header 23.

The hinge 14 has a lip 3l) connected to the door member12 by means ofscrewsV 32 and a'lip 34 connected to the upper header 26 bymeans ofscrews 36. The lips 30 and 34 of hinge 14 are pivotally connectedtogether by means of pin 37.

The inner portion22 of the spring 18 includes a plurality of slottedapertures 38, 39,' 40, 41 and 42. The apertures 39 and 41 straddle bolts43 and 44 which rigidly clampv the inner portion 22 of spring 18 betweena first plate 46, a wedge. 48 and a second plate 50. The bolts 43 and 44have liat heads 52, one of which is shown in FIGURE 2, which arecounter-sunk in the plate 46 so that the plate 46 will present a smoothsurface to the lip 34 of hinge 14. Y

The outer portion 20 of the spring 1S is connected to the door 12 bymeans ofa pair of brackets 53, a pin 54, a roller 56 and a lip portion53. The forward ends of the brackets 53 are secured to the door 12 bymeans of suitable bolts 60 and the pin 54 passes through apertures 62 inthe upstandinglegs 63 of the forward ends of brackets 53 with the rollerl:'56 being rotatably mounted on the pin 54 intermediate the legs 63.The lip 5S includes an offset portion 64 which is attached to the outerportion 2t) of spring 1S by means of bolts 66. The outer portion 26 ofthe spring 18 extends under the roller 56 and the lip 53 extends abovethe roller 55 forming a rolling connection between the spring 18 and thedoor 12.

The rear portions 63 of the brackets 53 are secured to the lid 12 alonglip Si) of the butt hinge 14 by means of bolts 70 and include lingers 72which are engageable with the plate 46 to bring it into engagement withthe lip 34 of the hinge14 against the bias of the spring 1 8 when thedoor 12 is closed. It is to be noted that the structure just describeddoes not connect the spring 18 to the frame 16 and, thus, the springwould remain substantially parallel to the door 12 even though the doorbe pivoted through 90, as shown in FIGURE 4.

The assemblyV Vcomprising the plate 46, the wedge 4S, the inner portion22 of the spring 18 and the plate 5) may be secured to the frame 16 byinserting three bolts, one of which is shown at 74 in FIGURES 2 and 3,through the leading edge of the Wing 24, the upper header 25, the lip 34of the hinge 14, the plate 46, the wedge'43, the slotted apertures38,740 and 42 of spring 1S, and the plate 'S0 to threadedly engage nuts7o, which are rigidly aiiixed to the plate 50, with the bolts '74. Thespring 1S then acts to bias the door 12 to its closed position whereinthe door 12'will function as a pressure relief valve. When the pressurewithin the wing 24 acting on the door 12 exceeds Y that they are theonlythree that needg be removed when it is desired to open the doorlZ foraccess to the interior of wing 24. When the door 12 is closed afterhaving been opened for access to the wing 214, the fingers 72 `willforce the plate 46 back into engagement with the lip 340i the hinge 14against the bias of spring 18.`

VThe wedgel43 has a sloped forward portionSZrwhich serves to controlspring 18 in such a manner thatdoor 12 opens smoothly with the sameinterior pressure.

. In use, the three bolts 74 are employed to maintain the portion 2.2 ofthe spring 18 Vin rigid` connect-ion with the header 26 on one sideofthe hinge pin 37 while the portion k2t) of the spring 1S is maintainedin engagement withthe sleeve S6. f Spring 18 will -then bias the door 12toits closed position. When pressure inside the wing 24 acting on theinside of the door 12 becomes great enough to overcome the bias of thespring 18, the door 12 will open to relieve the pressure before itbuilds up sufficiently to damage the Wing 24. Once the excessivepressure condition has been eliminated, spring 18 Will again bias thedoor 12 into its closed position.

When it is desired to gain access to the interior of the leading edge ofwing 24, the three bolts 74 are removed, eliminating the connectionbetween the portion 22 of the spring 13 and the header 26 so that thedoor may be swung on the hinge 14 through a 90 arc without anyinterference from the spring 13. When the door 12 is closed, the fingers72 engage the plate 45, causing it to engage the lip 34. The bolts 74may then. be replaced so that the door V12 will again act as a reliefvalve.

Although it is sometimesy desirable to utilize a roller such as roller56 upon the pin 54, it has been found that this part may be eliminatedwithout detriment. In such case, the pin 54 is usually allowed to rotatefreely within the apertures 62.

An alternative embodiment of the outer portion 20 of the spring isillustrated in FIGURES 5 and 6. Therein, the lip portion 5S previouslydescribed is eliminated and a hook-like pin receptacle 73 is provided inthe extremity of the spring 18.v When the door member 12 swings openresultant from pressure buildup, relative movement of the outer portion20 of the spring 1S with respect to the bracket 63 and the pin 54 takesplace since the door member 12 is pivoted about a hinge point and theinner portion 22 ofthe spring 18 remains stationary. Therefore, theouter portion of door member 12 moves outward with respect to thereceptacle '78, carryingV the pin 54. Even` tually the relative movementresults in an engagement of the pin 54m the receptacle 78, .as shown in'FIGURE 5. This provides means whereby the door is prevented fromopening more than a predetermined amount. The natural vresiliency ofthespring 18, in addition to the force of air passing over the wing, servesto close the door once the internal pressure is relieved.

' While the particular dual-purpose door herein shown and described indetail is fully capable of attaining the objects and providing theadvantages hereinbefore stated,k

it is to be understood that it is merely illustrative of the presentlypreferred embodiment of the invention and that no limitations areintended to the details of construction or ydesign herein shown otherthan as defined in the appended claims.

What is claimed is:

1.A In combination with the leading edge of an airplane wing, adual-purpose door for controlling the pressure within said wing andpermitting access vto the interior of said wing comprising:

(a) a door member swingably mounted in an opening in said leading edgefor ,controlling access to said wing and for relieving excess pressurefrom the interior of said wing; and

(b) resilient means having lone endconnected to said door member andanother end connected to said leading edge for biasing said door memberagainst the pressure within said wing a predetermined amount,.

said other end being releasable from said leading edge for freeing saiddoor member to swing without restraint, said resilient means comprisinga leaf spring having one end pivotally connected to said door member andanother'end-clamped between rst and e second plates, said second platebeing engageable with said leading edge and movablerelative thereto forreleasably securing said other end to said leading edge. 2.l Thecombination of claim I having a pin horizontally mounted on said doormember, said leaf spring comprising a lip portion extending toa pointsuperjacent said pin 'to form said pivotal connection. i

3. The combination of claim 1 including:

(a) ng'er means having a base portion rigidly aiixed to said door memberadiacent said other end of said spring and another portion engageablewith said second plate to bring it into engagement with said leadingedge when said door member is closed.l

4. The combination of claim 1 having a pin horizontal- 1y mounted onsaid door member, means upon said leaf spring engageable by said pin forpreventing opening of said door more than a predetermined amount.

5. The combination of claim 1 having detent means mounted on said door,and means upon said leaf spring adapted for engagement by said detentmeans to control the extent of door opening.

6. In an aircraft wing having a leading edge, the im'-V through saidopening and to serve as a pressure relief valve to relieve excesspressures building up in said leading edge;

(c) a leaf spring having one end pivotally connected to said door andanother end positionable adjacent said header; l

(d) a plate connected to said other end of said spring;

(e) finger means rigidly connected to said door adjacent said other endof said spring for engaging said plate to bring said plate intoengagement with said header when said door member is closed; and

(f) threaded nut means rigidly aiXed to said plate and i 6 beingpositionable over the apertures in said header for selective engagementby bolt means to rigidly connect said other end of said spring to saidheader at predetermined times. l 7. A dual-purpose door for controllingthe pressure Within a pressurized chamber and for permitting access tosaid chamber comprising:

(a) a door member swingably mounted in an opening in an exterior wall ofsaid chamber for controlling access to said chamber and for relievingexcess pressure from the interior of said chamber; and

(b) resilient means having one end connected to said door member andanother end connected to the eX- terior Wall of said chamber for biasingsaid door against the pressure Within said chamber a predeterminedamount, said other end being releasable from the exterior Wall forfreeing said door member to swing without restraint, said resilientmeans comprising a leaf spring having one end pivotally connected tosaid door member and another end clamped between first and secondplates, said second plate being engageable with the exterior wall andmovable relative thereto for releasably securing said other end totheleading edge.

References Cited in the le of this patent UNITED STATES PATENTS 756,869Mansfield Apr. 12, 1904 2,748,855 Siems et al. June 5, 1956 2,767,735Darling Oct. 23, 1956 `2,774,116 Wolverton v Dec. 18, 1956 3,013,579Gilliam Dec. 19, 1961

1. IN COMBINATION WITH THE LEADING EDGE OF AN AIRPLANE WING, ADUAL-PURPOSE DOOR FOR CONTROLLING THE PRESSURE WITHIN SAID WING ANDPERMITTING ACCESS TO THE INTERIOR OF SAID WING COMPRISING: (A) A DOORMEMBER SWINGABLY MOUNTED IN AN OPENING IN SAID LEADING EDGE FORCONTROLLING ACCESS TO SAID WING AND FOR RELIEVING EXCESS PRESSURE FROMTHE INTERIOR OF SAID WING; AND (B) RESILIENT MEANS HAVING ONE ENDCONNECTED TO SAID DOOR MEMBER AND ANOTHER END CONNECTED TO SAID LEADINGEDGE FOR BIASING SAID DOOR MEMBER AGAINST THE PRESSURE WITHIN SAID WINGA PREDETERMINED AMOUNT, SAID OTHER END BEING RELEASABLE FROM SAIDLEADING EDGE FOR FREEING SAID DOOR MEMBER TO SWING WITHOUT RESTRAINT,SAID RESILIENT MEANS COMPRISING A LEAF SPRING HAVING ONE END PIVOTALLYCONNECTED TO SAID DOOR MEMBER AND ANOTHER END CLAMPED BETWEEN FIRST ANDSECOND PLATES, SAID SECOND PLATE BEING ENGAGEABLE WITH SAID LEADING EDGEAND MOVABLE RELATIVE THERETO